Troubleshooting this problem could be very simple: try connecting the VPN with and without "Set nameserver" selected. If one way or the other solves your problem, you're done!

OpenVPN is such a powerful tool with so many options, and computer configurations are so varied, that it is impossible to have an exhaustive troubleshooting guide. This guide is meant for the most common setups, so if it doesn't apply to your situation, or doesn't help, see the Support page for guidance.

This page assumes that you are successfully connected to a VPN server. If not, or if you aren't sure, look at Common Problems.

If OpenVPN is connected to the server but you can't access the Internet

After connecting, if you can't reach the Internet, it's likely that your setup has

A DNS problem and/or

A routing problem and/or

A problem with the VPN server

Tunnelblick includes the ability to diagnose some DNS problems and will warn you about some common configuration problems.

Check for a DNS problem:
If OpenVPN connected to the server properly, but you are having trouble connecting to websites, the first thing to find out is if there is a DNS problem. To check that, try to access a website by using its IP address instead of its name. If the IP address works, but the name doesn't, there is a DNS problem. (Consider the IP address to be "working" if any of the webpage loads.)

If you don't have a DNS problem then there is something else going on. See the Support page for guidance.

If you have a DNS problem:

See if your network settings manually specify a DNS server. If they do, that server will be used even when the VPN is active unless you put a check in "Allow changes to manually-set network settings" on Tunnelblick's "Advanced" settings page. If the manual DNS server is your ISP's DNS server, it is probably set up to ignore queries that come from outside the network. When you are connected to the VPN, your queries come from the VPN server, which is probably outside the ISP's network, so the ISP's DNS server will ignore your request. You should set up your computer to use a free public DNS server (see How to use a different DNS server, below) while the VPN is active.

If your DNS settings are specified by DHCP, check your DNS settings both before you connect to the VPN and while you are connected.

If the DNS settings are different, the VPN is using a DNS server specified by the VPN setup. Contact the person who maintains your VPN server to find out why that DNS server is not functioning properly.

How to check your DNS settings

Launch System Preferences,

Click "Network"
Your DNS server list is one of the entries on the right. It is a list of IP addresses, separated by commas. macOS will use the first one unless it fails to respond to requests, in which case it will try the second, then the third, etc.

Note: If the DNS server list is dimmed (grayed out), it was set via DHCP, not manually.

How to use a different DNS server

There are two ways to set up a different DNS server:

Use a different DNS server whether or not a VPN is active

You can set your computer up to use a different DNS server all the time. Google Public DNS is free, and OpenDNS has a free version. There are lots of others. To use such a DNS server all the time (whether or not a VPN is connected):

Launch System Preferences,

Click "Network"

Copy/paste the following "8.8.8.8,8.8.4.4,208.67.222.222,208.67.220.220" (without the quotation marks) into the box to the right of "DNS Server"

This will set up your computer to always (whether or not you are connected to the VPN) use two Google DNS servers and two OpenDNS servers (in that order). Substitute the addresses for the DNS provider of your choice if you want.

Use a different DNS server only when the VPN is active

Note: This will only work if you specify "Set nameserver" in Tunnelblick's settings for the configuration.

Add a line to your OpenVPN configuration file for each DNS server: "dhcp-option DNS address" (substitute the DNS server's IP address for address). (To add two servers, add two lines to the OpenVPN configuration file, one for each server.)

If OpenVPN is connected to the server but your IP address does not change

If you have a check in the "Check if the apparent public IP address changed after connecting" checkbox on the "Settings" tab of Tunnelblick's "VPN Details" window, and your IP address doesn't change after connecting, a window will pop up to notify you.

If OpenVPN connects to the server properly but your IP address does not change, your OpenVPN setup needs to include the "--redirect-gateway" option. By default, OpenVPN only sends some traffic through the VPN — traffic that is specifically destined for the VPN network itself. The "--redirect-gateway" option tells OpenVPN to send all IPv4 traffic through the VPN.

There are three ways the option can be added; you need only use one:

Put a check in the "Route all Ipv4 traffic through the VPN" checkbox on the "Settings" tab of Tunnelblick's "VPN Details" window.

How to test your IP address

Note: tunnelblick.net does not use Javascript, other client-side scripting, plugins, trackers, beacons, or web bugs, and it does not carry advertising. It does not store cookies or any other data on your computer (except as noted in the tunnelblick.net privacy policy).

If you have checked "Check if the apparent public IP address changed after connecting", the IP address will be displayed in the Tunnelblick menu while you are connected: